Liquid crystal displays are widely used for displays of computers and television receivers. Active matrix type liquid crystal panels including thin film transistors (TFT) are frequently used for address elements in liquid crystal displays.
In such an active matrix type liquid crystal panel using TFT, recently, a panel has been realized with the use of an SHA (Super High Aperture Ratio) technology, which is a super high aperture ratio technology that achieves higher luminance, higher contrast, and lower electric power consumption.
FIG. 12 is a diagram for describing a configuration example of a picture element electrode in a TFT liquid crystal panel using the SHA technology; FIG. 12(A) is a plane schematic view of a picture element electrode unit; and FIG. 12(B) is a schematic configuration diagram of a sectional side view of the picture element electrode unit. In FIG. 12: 11 is a picture element electrode; 12 is TFT; 13 is a source line; 14 is a gate line; 15 is a parasitic capacitance; and 16 is a special resin.
A plurality of the picture element electrodes 11 is formed in a matrix shape on an active matrix substrate. The TFT 12 is a switching element disposed for each picture element electrode 11 and is connected to each picture element electrode 11. The gate electrode of the TFT 12 is connected to the gate line 14 for supplying a scan signal and the TFT is driven and controlled by a gate signal input to the gate electrode. Each picture element corresponding to each picture element electrode 11 is referred to as a sub-pixel and is used normally for displaying one color of RGB. A group of three picture elements of RGB is referred to as a pixel.
The source electrode of the TFT 12 is connected to the source line 13 for supplying a display signal (data signal) and when the TFT 12 is driven, the display signal is input to the picture element electrode 11 through the TFT 12. The gate line 14 and the source line 13 are disposed orthogonal to each other around the picture element electrode 11 disposed in a matrix shape.
In the liquid crystal panel with the SHA configuration, the special resin 16 is used for an interlayer dielectric film to acquire a super high aperture ratio. As shown in FIG. 12(B), the picture element electrode 11 is disposed above the source line 13 via the special resin 16 to have a three-dimensional structure. This inevitably generates the parasitic capacitance 15 between the picture element electrode 11 and the source line 13.
Since the parasitic capacitance 15 is created between the source line 13 supplying the display signal to one picture element electrode and the source line 13 supplying the display signal to another picture element electrode adjacent to the picture element electrode, two capacity couplings are formed for one picture element electrode.
If the aforementioned active matrix type display apparatus has, for example, a plane structure (Non-SHA) without the three-dimensional structure described above and does not have the parasitic capacitance 15, the voltage of the source line 13 is applied to the picture element electrode 11 only when the gate line 14 is turned on and this electric charge is retained for one frame period when the gate line 14 is turned off. However, if the capacity coupling is generated due to the parasitic capacitance 15, the electric charge retained by the picture element electrode 11 becomes unsteady due to leakage or application through the parasitic capacitance 15. This factor causes crosstalk and a problem of image quality deterioration.
FIG. 13 illustrates spectral characteristics of a typical color filter and, as shown in FIG. 13, transmissivity of primary colors of the color filter overlap each other and have an effect on color purity of display color. Such an effect on display color is induced by optical factors such as leakage light from a polarization plate as well as wavelength dependency of the light transmissivity and is a kind of optical crosstalk.
With regard to such a problem, for example, patent document 1 discloses an active matrix type liquid crystal display apparatus that achieves a balance of capacities between one picture element electrode and signal lines on both sides to prevent a display defect such as crosstalk by extending a shield electrode along a signal line from an auxiliary capacity line intersecting with the signal line, by superimposing one edge side of the shield electrode on the picture element electrode, by superimposing the other edge side on adjacent picture element electrode, and by differentiating the superimposing lengths L1, L2.
Patent document 2 discloses a crosstalk correcting apparatus of a plasma address type display apparatus compensating diffusion in an insulating layer of a drive voltage (a voltage applied to liquid crystal), which generates and outputs an output signal DG[n]=input signal SG[n]+correction signal H((SG[n]−SR[n])+(SG[n]−SB[n])) for a picture element G[n].
Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-206560
Patent Document 2: Japanese Laid-Open Patent Publication No. 2000-321559